The Next Generation Network (NGN) is characterized, among other things, by the prevalent use of the Internet Protocol (IP) for end-to-end packet transfer. But the main mission of the NGN is flawless support of a wide range of applications, including real-time multimedia, over the packet infrastructure. This requirement and those for security and reliability together are so broad and diversified that one can envision the NGN as a distributed general-purpose computing engine. Here, the early Internet model of the network as a “best-effort” pipe is converging with the modern combined Information Technology and Telecommunications model of the network as a super-large computer. Consequently, the responsibilities of the NGN expand—from merely supporting connectivity—toward assuring the quality of services comprehensively.
The key to fulfilling this expanded duty is dynamic resource management. Indeed, among the most active topics in the present research and development on the NGN is real-time application-driven resource management. The resources that need to be managed include                1. Bandwidth;        2. IP addresses;        3. Transport (TCP and UDP) ports;        4. Various database records; and        5. MPLS label-switched-paths,among many others. In fact, the very multitude of these “others” is what necessitates an abstraction of the resource concept and the development of the appropriate mechanisms based on this abstraction.        
There is a need to concentrate on the application-driven and real-time aspects of resource management that are of particular importance in the NGN because of the need for coupling the service control and transport resource control. First, such coupling enables the fast introduction of new services (such as IP telephony, IP TV, and IP gaming) for which performance is a key differentiator. Second, it allows the services to evolve independently of the packet transport technology.
The IETF RFC 2753 specifies a framework for policy-based admission control. This framework underpins the IP Multimedia Subsystem (IMS) service-based local policy control, as specified in 3 GPP TS 23.207. That, in turn, has become the basis for the resource- and policy-based admission control mechanisms being standardized in both the ETSI (or rather ETSI TISPAN project, to be specific) and ITU-T Study Groups 11 and 13.
The emerging standard mechanisms have been designed to allow the admission decision for a service request (IMS- or non-IMS-supported) to take into consideration both policy and transport resource availability. They enable performance assurance and border control (e.g., NAPT, NAT traversal, and gating) through bridging service control and transport resource management. The mechanisms are defined as part of the Resource and Admission Control Subsystem (RACS) in the ETSI TISPAN project and the Resource and Admission Control Functions (RACF) in the ITU-T, however, functionalities for Real-Time Application-Driven Resource Management in Next Generation Networks have yet to be developed.